1. Field of the Invention
The present invention relates generally to the field of agriculture and plant genetics. More particularly, it concerns genetically modified plants displaying modified cell wall composition, resulting in altered levels of lignin, cellulose, and/or hemicellulose.
2. Description of Related Art
A variety of fuels may also be produced from sugars and starches as well as from lignocellulosic based biomass which constitute the most abundant biomass on earth. However, the types of biofuels that can be efficiently produced from plant mass depend upon the content of component material such as lignin. Likewise, biomass content dictates the nutritional value of plant mass as animal feed.
The principal source of fermentable sugar in lignocellulosic biomass is cellulose. In typical lignocellulosic biomass used for ethanol production, cellulose accounts for between 35 to 50% of the mass. Cellulose is a long chain polysaccharide carbohydrate, composed of repeating cellobiose (β-1,4 glucose disaccharide) units. Hemicellulose also contributes to the fermentable sugar content of lignocellulosic biomass. It comprises about 20 to 35% of lignocellulosic biomass mass, and is a mixture of a variety of sugars including arabinose, galactose, glucose, mannose, and xylose, and derivatives of such sugars. The third major component of lignocellulosic biomass, lignin, is not a sugar based fermentable polymer. Lignin is a complex polymer of hydroxylated and methoxylated phenylpropane units, linked via oxidative coupling and comprises about 12 to 20% of lignocellulosic biomass.